The American space agency, Nasa, has launched a satellite to monitor how charged particles from the Sun interact with the Earth.

The $154m Imager for Magnetosphere-to-Aural Global Exploration - or
Image - is the first satellite dedicated to studying the entire magnetosphere, an invisible field that envelops far beyond Earth, and provide accurate space weather forecasts.

A Boeing Delta II rocket boosted the Image satellite into orbit without any problems, officials said.

"It's going great," said James Burch, Image's principal investigator.

Nasa workers show off the $154m satellite

"Our orbit is perfect. We've turned on several systems on the spacecraft and we're getting data."

However, it will be about 40 days before Image is ready to send back full movies of the magnetosphere, using the four 250m (820ft) antennae which make it the longest artificial object in space.

Each second, the magnetosphere is bombarded by charged particles from the Sun, either in the form of a solar wind or the more violent events known as coronal mass ejections.

These contain vast clouds of charged particles - travelling at more than one million kilometres an hour - generating their own magnetic fields.

Two-year mission

During the satellite's two-year mission, scientific instruments will study the interaction of the solar wind with the Earth's protective magnetosphere.

It will also link up with the National Oceanic and Atmospheric Administration in the United States for use in space weather forecasting, because charged particles can damage satellites or even knock out electricity supplies on the ground.

Image's launch comes as the Sun's energy outbursts are reaching the peak of an 11-year cycle.

During the last solar maximum in 1989, a major geomagnetic storm caused a
widespread blackout in Quebec and knocked out some US Defence Department satellites.

To get the big picture of the magnetosphere, Image's highly elliptical orbit ranges in altitude from 1,000km (640 miles) to over 45,000km (28,000 miles).

Other satellites have only taken snapshots of the region that they happened to be flying through.